Magnetic fixture



May 14, 1946.

J. H. BARRETT MAGNETIC FIXTURE Filed May 29', 1944 III I rwlraviiia= l evil vii INVENTOR. JOHN H. BARRETT ATTORNEY Patented May 14, 1946 MAGNETIC FIXTURE John H. Barrett, Hudson, Mass., assignor to The I Lapointe Machine Tool Company,

Hudson,

Mass, a corporation of Maine Application May 29, 1944, Serial No. 537,940

2 Claims.

This invention relates to a magnetic fixture on which a piece of work may be supported for grinding or other machine operations.

It is the general object of my invention to provide an improved magnetic fixture for such purposes, which may be conveniently adjusted so that the work may be securely held at any selected angle relative to the plane of the base of the fixture.

A more specific object is to provide a magnetic fixture having an angularly adjustable workholding element, together with worm and worm gear mechanism for adjusting and holding said element, and with additional means for clamping the parts in adjusted position. The magnetic force which holds the work in the fixture also aids in holding the fixed and movable parts of the fixture in adjusted angular relation when the fixture is energized.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawing, in which Fig. l is a side elevation of my improved magnetic fixture;

Fig. 2 is a front elevation, looking in the direction of the arrow 2 in Fig. 1;

Fig. 3 is a detail sectional view, taken along the line 33 of Fig. l; and

Fig. 4 is a sectional side elevation, taken along the line l4 of Fig. l.

Referring to the drawing, my improved magnetic fixture comprises a base I and a work support I2 each comprising a series of relatively thin plates which are alternately of magnetic and non-magnetic material. The middle section M of the base It! is of increased width and preferably of magnetic material, and the middle section I5 of the work support I2 is similarly of increased width and of magnetic material. The two end sections I6 and ll of the base I0 and support I2 are also of double thickness for a purpose to be described.

The base II] has a concave cylindrical recess 20 (Fig. 4) and the work support I2 has a cylindrical surface 2I engaging the surface 20 and supported thereby. The part are held in assembled relation by plates 22 and 23 (Fig. 2) fixed to the end of the work support I2 by screws 24 and each provided with a segmental rib 25 (Fig. 3) slidably fitting a segmental groove 26 in the associated end plate I6 or I! of the base III. The base and work support are thus securely held in assembled relation.

The parallel thin plates forming the work support I2 may be secured together by longitudinally extending non-magnetic rods 39, and the corresponding parts of the base I0 may be sim ilarly secured by non-magnetic rods 3!. Threaded studs 33 are fixed in the end plates 56 and ll of the base l0 and are provided with clamping nuts 34 and interposed washers 35.

The studs 33 extend through slots 40 in the end plates 22 and 23, and the washers 35 are clamped against the end plates to hold the work support in adjusted angular position. The base may be graduated to coact with an index line 42 as shown in Fig. l, the graduations indicating the angular setting of the Work support,

The work support I2 is shown as cut awa to provide work-engaging surfaces 44 and 45, preferably at 90 to each other and adapted to support a rectangular piece of work W at any desired angle relative to the base I0.

For conveniently and accurately adjusting the work support I2, I provide the work support with a series of worm gear teeth (Fig. 4), which teeth are engaged by a worm 5| formed on a short shaft 52 rotatable in bushings 53. The ends of the shaft 52 are squared to receive a socket wrench, and the bushings 53 are threaded in a cylindrical transverse opening 55 in the base It. The bushings 53 preferably have fine-pitch threads which are a relatively snug fit in the threaded portions of the opening 55.

The bushings are screwed into the opening 55 until they snugly engage the opposite ends of the threaded middle portion of the worm shaft 52, thus preventing axial movement thereof. By turning the worm shaft, the work support I2 may be angul-arly adjusted. The worm itself locks the work support and prevents angular displacement thereof in the base I0, Any lost motion between the worm and worm gear teeth may thereafter be taken care of by tightening the clamping nuts 34.

Having thus described m invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. A magnetic fixture comprising a base and a work support each formed of alternated ma netic and non-magnetic plates secured in assembled relation and each having a middle section of substantial thickness, said base having a concave recess and said support having a convex surface fitting said recess, the middle section of said support having segmental worm gear teeth in its convex surface and the middle section of the base having a transverse cylindrical recess therein, a worm shaft rotatably mounted in said recess, means to restrain said shaft from axial movement therein, and a worm on said shaft engaging said worm gear teeth, and rotation of said worm being efiective to angularly adjust said work support.

2. A magnetic fixture comprising a base and a work support each formed of alternated magnetic and non-magnetic plates secured in assembled relation and each having a middle section of substantial thickness, said base having a concave recess and said support having a convex surface fitting said recess, the middle section of said support having segmental worm gear teeth in its convex surface and the middle section of the base having a transverse cylindrical recess therein, a pair of spaced bushings threaded in said cylindrical recess and axially adjustable therein, a worm shaft rotat-ably mounted in said bushings but restrained from axial movement thereby, and a worm on said shaft abutting the inner ends of said bushings and engaging said worm gear teeth, and rotation of said Worm being eil'ective to angularly adjust said work support.

JOHN H. BARRETT. 

